PROJECT SUMMARY/ABSTRACT Obesity prevention efforts are increasingly focused on early childhood. Emerging evidence suggests that the emotional quality of interactions between parents and children impacts risk for obesity and self-regulation may be an explanatory mechanism. However, parent-child interactions are traditionally observed during play, and mealtime interactions have not been studied over time in relationship to children's obesity risk. Further, which aspects of self-regulation are involved is unclear. Children born preterm have risks for obesity that are similar to children born at term, and preterm children are at higher risk for deficits in self-regulation. The objective of this application is to conduct a longitudinal study of toddlers (of all gestational ages) to determine how the quality of parent-child interactions observed in mealtime and play settings in the home and laboratory impacts changes in weight and adiposity through preschool-age, and to identify the aspects of self-regulation that are involved. Our central hypothesis is that trajectories of parent-child mealtime interaction will differ and predict risk for obesity at 42 months more robustly than observations of parent-child interaction during play, with gestational age and temperamental reactivity as effect modifiers, and emotion regulation as the aspect of self- regulation most strongly associated with obesity. The rationale for the current project is that strategies to prevent obesity in young children are urgently needed and parent engagement will be crucial to their success; studying parent-child interaction over time and across contexts, with children of all gestational ages, will facilitate identification of modifiable targets for obesity prevention. The proposal has three specific aims: 1) to characterize trajectories of parent-child mealtime interactions across the toddler to preschool period relative to parent-child interactions in play, 2) to identify parent-child mealtime interactions that increase risk for obesity, and 3) to determine the aspects of self-regulation that predict healthy weight in preschool-aged children and identify precursors. Our approach to accomplish these aims will be a prospective study of 250 children enrolled at 18 months and assessed at 24, 36, and 42 months of age in our laboratory and in their homes. Parent-child interaction during play and during mealtimes at home and in a standardized buffet lunch in the laboratory will be observed and objectively coded. Self-regulation at preschool-age will be assessed using a battery of objective tasks and parent-report. The expected outcomes of this research will be detailed understanding of the aspects of self-regulation and parent-child mealtime interactions that are associated with risk for obesity in early childhood. The project is innovative in bringing concepts and methods from developmental science to the challenge of childhood obesity and utilizing objective coding of observed parent-child interactions in mealtime and non-mealtime contexts over time and with children of all gestational ages. The project is significant because it will bring a dyadic perspective to research on parenting and childhood obesity and what is learned can be applied to have a positive impact on the health and well-being of children and families.